Brown meat with onions and garlic in large saucepan; drain.,Return meat mixture to pan.,______,Bring to boil; simmer on medium-low heat 10 min.,or until most the liquid is cooked off, stirring occasionally.,Meanwhile, melt butter with oil in large ovenproof nonstick skillet on medium-high heat.,Stir in potatoes; spread to form even layer on bottom of skillet.,Use back of spatula to press potato mixture onto bottom of skillet.,Cook 5 min.,on each side or until golden brown on both sides, reducing heat if potatoes are browning too quickly.,Heat broiler.,Spoon meat mixture over potatoes; top with tomatoes and cheese.,Broil, 4 inches from heat, 2 to 3 min.,or until cheese is melted.